"Now that the plant is actually closed and potentially for sale, there’s probably no better fit than Calera," founder Brent Constantz told the Sentinel on Friday. "We’re not thinking about doing anything real soon, but there is a possibility we could resume cement manufacturing there."

Constantz, a cement trailblazer, venture capitalist and consulting professor at Stanford University, has not discussed any deal with Davenport plant owner Cemex. But he and his staff are familiar with the complex and have even plotted how it could be retooled for their environmentally-friendly brand of cement.

Calera’s Moss Landing plant, a pilot operation that began less than two years ago, makes its novel cement by using carbon dioxide pollution - thus serving the dual goals of cement production and removing harmful greenhouse gases from the atmosphere.

Last month, the Davenport plant was permanently shut down, following a 10-month suspension. Its Mexico-based owner cited financial and falling international demand for cement. Cemex officials have not publicly discussed the future of the site, but said it’s up for negotiation."We are happy to discuss all meaningful business opportunities," Cemex spokeswoman Jennifer Borgen said Friday.

The county, meanwhile, has also begun to look at how the property might be used, particularly if the old cement plant is retired, as many have speculated it will be. Doing something different on the manufacturing site could involve a lengthy and costly cleanup, which would be averted with a revived cement operation.

"It’s always easier to reutilize an existing structure and type of use than put up a new structure," said county Principal Planner Glenda Hill.

Calera’s model of making cement rests in carbon dioxide emissions. The Moss Landing cement facility is tied to the nearby Dynegy power plant along Elkhorn Slough where the utility’s exhaust is combined with seawater in a proprietary process to produce cement.

"It’s a twofer," Constantz explained. "We’re addressing the CO2 coming form electric power and we’re avoiding the CO2 that would have been produced (in a normal cement process)."

The concept, Constantz says, can be altered slightly to work in Davenport. Instead of harnessing carbon dioxide from a power plant, he says, Calera engineers could fire up the old cement plant and use its emissions to run a new cement operation of their own.

The result would be the production of two types of cement, the common Portland cement from the old plant and cement from the new plant, which would ultimately be blended together, Constantz says. The operation, taken as whole, would be "carbon neutral" or "carbon negative," he adds.

"I think it’s very doable and well within our bandwidth," he said. "It would be a great worldwide demonstration facility."

Calera, which started in 2007, is headquartered in Los Gatos, where its research labs create and test its technology. Between Los Gatos and Moss Landing, the company employs about 130 people.

Many of the Moss Landing employees, Constantz says, are former Cemex workers.